base64

[Trevor Perrin <trevp@trevp.net>]

In the wd-01 schema, the client sends all input documents in base64 encoding.

Pros:
  - Works the same way for XML or binary data
  - Avoids ID collisions between different input documents, or between the 
input documents and the protocol message (which assigns its own ID to each 
<InputDocument>).  But I guess the XML inside each <InputDocument> would be 
processed under processContents=skip, and the schemas wouldn't be available 
anyways..  so maybe ID collisions don't matter?
  - Protects the InputDocument if the request is reformatted or 
canonicalized - things like changing whitespace, or normalizing attribute 
order and attribute value delimiters (double-quotes or single-quotes), 
could change the InputDocument so the server isn't signing what the client 
sent.  I worry that a SOAP intermediary or something between client and 
server could make changes like that.  If the server canonicalizes the input 
document before signing, then it might erase these changes.  However, if 
the client has already canonicalized, then the server would expect to use 
the bytes as is.

I'm not sure how real the last two concerns are.

Cons:
  - messages would be more readable if we sent XML in the clear.
  - messages would be smaller.

Thoughts?

Trevor